Stabilizing solution of tetra-alkyl lead compounds



Patented 1, 1942 STABILIZING SOLUTION F TETRA-ALKYL LEAD COMPOUNDS TroyLee Cantrell, Lansdowne, and Carlton Louis Suplee, Malvern, Pa.,assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation ofPennsylvania No Drawing. Original application January 31,

1940, Serial No. 316,686. Divided and this application March 31, 1942,Serial No. 437,088

4 Claims. (CI. 4473) This invention relates to stabilizing solutions oftetra-alkyl lead compounds; and it comprises a method of stabilizingsaid solutions particularly ethyl gasoline wherein the development of ahazy appearance is inhibited by adding to such solutionssmall'quantities of cinnamylidene aniline; all as more fully hereinafterset forth and as claimed.

This application is a division of our copending application, Serial No.316,686, as filed January 31, 1940.

It is customary in the production of so-called ethyl gasoline to add toa good grade of gasoline a small amount of a tetra-alkyl lead compound,usually tetra-ethyl lead to reduce the tendency of the gasoline to causeknocking in high compression gasoline engines. The amount of tetra-alkyllead compound added to a gasoline depends upon the nature of thegasoline and the desired anti-knock rating. Tetra-ethyl lead iscustomarily added to the gasoline in the form of a concentrate calledethyl fluid which is a solution containing a mixture of tetra-ethyllead, alkyl di-halide (e. g., ethyl di-bromide or ethyl di-chloride orboth) and a small amount of a dye to impart a distinctive color to thegasoline. The function of the alkyl di-halide is to limit the formationof lead oxide from tetra-alkyl lead in the cylinders of the engine byforming volatile halides of lead which are carried out in the exhaust.The ethyl fluid is added to the gasoline in a quantity suflicient toproduce the desired anti-knock rating and in some cases a relativelysmall amount may be required, 'while, in other cases, for example, inthe preparation of certain aviation grades of gasoline, a relativelylarge amount may be added. Gasoline to which a large amount oftetra-ethyl or other tetra-alkyl lead has been added is often referredto as a heavily leaded gasoline.

Although tetra-alkyl lead compounds, and, in

particular tetra-ethyl lead, are particularly efficient for impartinganti-knock properties to gasoline, their employment is not entirely freefrom disadvantage. For one thing, leaded gasoline tends to develop ahazy appearance upon standing, particularly in the presence of strongsunlight. For example, in direct sunlight in the summer time, ethylgasoline may develop a perceptiblehaziness after an hour or two ofexposure, and longer periods of exposure result in a very markedhaziness and precipitation occurs. observed in the ethyl fluid itself.

The formation of haze in gasoline is objec 55 5 to This phenomenon.- isalso sometimes tionable because the gasoline is not as marketable as aclear product; customers prefer a product which is crystal clear. Afurther and perhaps more important objection is that a reduction in theoctane rating of gasoline is frequently associated with haze formation.Also damage is likely to occur in the fuel lines and carburetor. Thedevelopment of haze in ethyl fluid itself is also objectionable, becausewhen a hazy ethyl fluid is blended with gasoline to form ethyl gasoline,the haze is introduced into the fuel with all its attendantdisadvantages.

An object achieved by this invention is to provide solutions oftetra-alkyl lead compounds,

such as ethyl fluid and ethyl gasoline which are stabilized against hazeformation.

We have found that haze formation in solutions. of tetra-alkyl leadcompounds, such asethyl fluid and ethyl gasoline, can be very materiallyreduced by incorporating in such solution small quantities, proportionedon the amount of tetra-alkyl lead compound in solution, of a compoundhaving the formula and known as cinnamylidene aniline.

Cinnamylidene aniline may be added with advantage to solutions generallyof tetra-alkyl lead compounds and more particularly to all types ofleaded gasoline. The manner of incorporating the cinnamylidene anilinein solution of tetra-alkyl lead compounds is not critical. It may beincorporated in the ethyl fluid at any stage during the preparationthereof, or it may be incorporated in the gasoline prior to the additionof ethyl fluid, along with the ethyl fluid, or subsequent to blendingthe ethyl fluid with the gasoline.

Even very small amounts of cinnamylidene aniline are suflicient to exerta substantial stabilizing effect against light in fluids containingtetra-alkyl lead compounds. In general with higher percentages oftetra-alkyl lead compounds, higher amounts of cinnamylidene anilin arerequired. Within the range of about 0.01 to about 1 per cent by weightof tetra-ethyl lead in solution, a substantial stabilizing effect isexerted by from about 3 to about pounds .of cinnamylidene aniline perthousand barrels of gasoline. Within the range from about 0.02 to about0.40 per cent by weight of tetra-ethyl lead in solution, whichrepresents a commercial range, it is advantageous to employ from aboutabout 20 pounds of cinnamylidene aniline per thousand barrels ofgasoline. Such amounts will exert a marked stabilizing effect againstlight and will produce a commercial ethyl gasoline which issatisfactorily stable to light under the usual conditions of exposure.

The application of cinnamylidene aniline to the stabilization ofsolutions of tetra-alkyl lead compounds against haze formation is notlimited to leaded gasoline and it may be incorporated directly in theethyl fluid with advantage. When cinnamylidene aniline is incorporatedin the tetra-alkyl lead concentrate, it stabilizes the concentrateduring storage and shipment, and the stabilized concentrate containingthe cinnamylidene aniline can then be added to gasoline to impartthereto both anti-knock properties and resistance to haze formation. Insuch case the amount of cinnamylidene aniline incorporated in the ethylfluid is generally somewhat greater than is required for stabilizationof the concentrate so that by the addition of the usual small amount ofethyl fluid to the gasoline a suitable stabilizing amount ofcinnamylidene aniline will be incorporated in the gasoline. Generallyfrom 1 to per cent by weight, based on the tetraethyl lead, ofcinnamylidene aniline very satisfactorily stabilizes commercialtetra-ethyl lead concentrates, such as ethyl fluid and' on adding .thestabilized concentrate to gasoline to produce ethyl gasoline, asatisfactorily stabilized ethyl gasoline is obtained.

The cinnamylidene aniline of our invention in;

addition to its stabilizing properties has other properties whichparticudarly recommend it for this use. It does not adversely affecttheoxygen stability of the gasoline. Samples of cracked ethyl gasolinecontaining cinnamylidene aniline have been aged and tested for oxygenstability and by the copper dish method for gum formation. The presenceof the cinnamylidene aniline didnot promote either oxygen instability orgum formation. Itis non-corrosive to common packline was noted. At theend of 5 hours exposure there was a small degree of haziness but a greataging materials such as steel, zinc, copper and tin and is compatiblewith the dyes commonly used in ethyl gasoline to give it a distinctiveappearance. It is sufficiently soluble in gasoline to accomplish theintended stabilization. Furthermore it is insoluble in water, which is adistinct advantage because contact with water will not result inleaching the stabilizer out of the gasoline. Continued storage ofgasoline containing cinnamylidene aniline does not affect itsstabllizing properties. Also cinnamylidene aniline can be readilyprepared from compounds available on the market at a relatively lowcost, and its mode of preparation is simple and inexpensive.

The following specific example will serve to illustrate the excellenthaze inhibiting properties of cinnamylidene aniline.

Example I.-Ethyl gasoline containing 0.1 per cent by weight oftetra-ethyl lead .(added in the form of ethyl fluid comprisingtetra-ethyl lead, ethylene dibromide and a dye) was treated withcinnamylidene aniline in the proportion of 20 pounds of the latter perthousand barrels of gasoline, the resulting solution was exposed for 5hours to sunlight and the appearance of the gasoimprovement over theappearance of the same gasoline containing no cinnamylidene aniline.This was considered a fair stabilization.

- While our invention has been described herein with reference tocertain specific embodiments and spcific examples thereof, we do notintend that our invention shall be limited to such embodiments andexamples except as hereinafter defined in the appended claims.

What we claim is:

1. A method of producing a light-stable solution of a tetra-alkyl leadcompound, which comprises incorporating in said solution cinnamylideneaniline in amount sufficient to inhibitthe formation of haze in saidsolution.

2. The method of claim 1 wherein the tetraalkyl lead compound istetra-ethyl lead.

3. A method of producing a light-stable antiknock motor fuel containinga tetra-alkyl lead compounclfwhich comprises incorporating in said motorfuel cinnamylidene aniline in amount corresponding to 0.01 to 1.0 percent by weight of the tetra-allryl lead compound. v

4. As an improved anti-knock motor fuel stable to light, a gasolinecontaining 0.02 to 0.4 per cent by weight of tetra-ethyl lead and about5 to 20 pounds of cinnamylidene aniline per thousand barrels ofgasoline.

TROY LEE CANTRELL. CARLTON LOUIS SUPLEE.

